chem exam 3

proteins

in the body are polymers made from 20 different amino acids that differ in characteristics and functions that depend on the order what are these?

how do proteins function

enzymes to regulate biological reactions such as digestion and cellular metabolism

structural proteins

provide structural components like collagen and keratin

contractile proteins

make muscles move like myosin and actin

transport proteins

carry essential substances throughout the body like hemoglobin and lipoproteins

storage proteins

store nutrients like casein and ferritin

hormone proteins

regulate body metabolism and the nervous system like insulin and growth hormones

enzyme proteins

catalyze biochemical reactions in the cells like sucrase and trypsin

protection proteins

recognize and destroy foreign substances like immunoglobulins

amino acids

the molecular building blocks of proteins that have a central alpha carbon bonded to an ammonium groip and a carboxylate group with a hydrogen atom and an R group

non-polar/hydrophobic amino acids

have hydrogen, alkyl, or aromatic R groups

polar amino acids

have R groups that interact with water, making them hydrophilic

polar neutral amino acids

contain hydroxyl, thiol, or amide R groups

polar acidic amino acids

contain a carboxylate R group

polar basic amino acids

contain an ammonium R group

peptide bond

an amide bond that forms when the -COO group of one amino acid reacts with. the -NH3 group of the next amino acid

primary protein

a particular sequence of amino acids held together by peptide bonds

secondary protein

amino acids form hydrogen bonds between the atoms in the backbone and atoms on the same or another peptide chain (alpha helix and beta pleated sheet)

tertiary protein

3D shape formed by the interactions and repulsions of amino acid residues in different parts of the chain

hydrophobic interactions

two amino acids having nonpolar R groups form a nonpolar center at the interior of the protein

hydrophilic interactions

the external aqueous environment and the R groups of polar amino acids residues that are pulled to the outer surface of most proteins

salt bridges

ionic interactions. between ionized R groups or polar basic and acidic amino acids

hydrogen bonds

form between the H of a polar R group and O or N of another polar amino acid

disulfide bonds

covalent bonds that form between the -SH groups of cysteine residues in a polypeptide chain

quaternary protein

two or more polypeptide chains or subunits

protein denaturation

interactions that stabilize secondary, tertiary, quaternary structures are disrupted which destroys the shape and renders the protein biologically inactive

protein hydrolysis

breaks up the primary structure by breaking the covalent peptide bonds that link the amino acids

protein denaturation

when a change disrupts the interactions among residues that stabilize the secondary, tertiary, or quaternary structures and does not affect the amide bonds among amino acids

enzymes

biological catalysts that increase the rate of a reaction by changing the way a reaction takes place, are not changed in the process of the reaction, and lower the activation energy of the reaction

how do enzymes lower activation energy

reducing the energy required to convert reactant molecules to products

substrates

small group of reacting molecules

active site

where one or more small groups of substrates bind to create a chemical reaction

absolute enzymes

catalyzes one type of reaction for one substrate

group enzymes

catalyzes one type of reactions for similar substrates

linkage enzymes

catalyzes one type of reaction for a specific type of bond

how to name enzymes

usually ends in -ase, identifies the reacting substance, and describes the function

allosteric enzymes

bind with a molecule and change the shape of the enzyme and can be positive or negative

inhibitors

molecules that cause a loss of catalytic activity and prevent substrates from fitting into the active sites and can be irreversible and reversible

reversible inhibition

cause a loss of enzyme activity that can be restored and can act in different ways but do not form covalent bonds with the enzyme

antimetabolites

competitive inhibitors

irreversible inhibition

enzyme activity is destroyed when the inhibitor covalently bonds with R groups of an amino acid that may be near the active site and the inhibitor changes the shape of the enzyme, which prevents the substrate from entering the active site

components of nucleic acids

nitrogen-containing base, sugar, and phosphate group

nucleosides

composed of a nitrogen-containing base and a sugar, either ribose or deoxyribose